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Incomplete Patching Lets Attackers Bypass MFA on SonicWall Gen6 VPNs

Researchers say missed manual LDAP steps left Gen6 appliances open to MFA bypass that let intruders move quickly inside networks.

Overview

  • ReliaQuest reported medium-confidence evidence that threat actors exploited CVE-2024-12802 across multiple environments between February and March 2026, gaining access to networks where SonicWall Gen6 devices looked patched but were not fully reconfigured.
  • The flaw stems from missing MFA enforcement for User Principal Name (UPN) logins, which lets an attacker with valid credentials authenticate without triggering the second factor.
  • SonicWall’s advisory requires six manual LDAP reconfiguration steps on Gen6 devices after applying the firmware update because the vulnerable LDAP settings remain unless deleted and rebuilt.
  • In the observed intrusions attackers brute-forced VPN credentials, bypassed MFA, performed fast reconnaissance, attempted to stage a Cobalt Strike beacon and a vulnerable driver, and in one case reached a domain-joined file server in about 30 minutes.
  • Defenders should verify completion of SonicWall’s manual remediation steps or upgrade to Gen7/8 firmware, search for indicators such as sess="CLI" and event IDs 238 and 1080, and treat Gen6 appliances as higher risk since they reached end-of-life on April 16, 2026.